A grid of fifteen smiley faces renders as SVG through React components. Each face randomly sizes its stroke width, eye radius, mouth width, and mouth radius using `Math.random`. The `Face` component composes `BackgroundCircle`, `Eyes`, and `Mouth`, where the mouth uses `d3.arc` to draw a half-circle path. The `FaceContainer` wraps children in a translated `<g>` element, and the app maps over `range(5*3)` to generate the grid.